High-power and high-efficiency green and blue laser diodes are successfully fabricated on semipolar plane and conventional c-plane GaN substrates, respectively. These lasers are promising light sources that meet the ITU-R Recommendation BT.2020 for future laser display applications.

A GaN-based vertical-cavity surface-emitting laser (VCSEL) formed with a spacer layer is designed and fabricated. The convex structure with a 15-nm step between center and peripheral area could result in a relative refractive index difference of 1.5%. Room-temperature continuous-wave operation of the VCSEL is demonstrated, showing a lower threshold current and a multi-mode operation. Thus, the convex structure for optical guiding plays an important role in the development of high-performance GaN-based VCSELs.

A pixel array of micro-light emitting diodes (μ-LEDs) based on a flip-chip structure and driven by a passive matrix is fabricated. The array is fabricated through multilevel metallization using a photosensitive polyimide inter-metal dielectric layer. The high reflectivity and large coverage of the p-type reflective electrode is essential to enhance the light output power of the μ-LED array.

Bias temperature instability (BTI) and related mechanisms are investigated in the E-mode GaN MIS-FET with LPCVD-SiN_x gate dielectric. Improved V_TH stability is obtained with PECVD-SiN_x interface protection layer, benefiting from the reduced trap density at/near the SiN_x/GaN interface. Combining the BTI tests and drain current 1/f noise analysis, we ascribe the V_TH instability to the trapping/detrapping of the pre-existing trap states located at SiN_x/GaN interface and/or in the gate dielectric.

A high-performance E-mode AlGaN/GaN MIS-HEMTs is fabricated with atomic layer deposited 5 nm SiON/16 nm HfON. Plasma nitridation is employed in every atomic layer deposition cycle to deposit SiON and HfON dielectrics. SiON is used as an interfacial layer to ensure a high-quality AlGaN/dielectric interface, and high-k HfON is employed to realize a large transconductance, a high on-state current, and a high on/off current ratio.

High resolution structural, morphological and electrical characterization of a graphene junction with an AlGaN/GaN heterostructure. An optimized graphene transfer procedure results in a uniform graphene coverage of the AlGaN surface. The impact of graphene wrinkles on the electrical properties of the heterojunction is investigated by conductive AFM.

An attractive feature of the recessed trapezoidal groove dual-gate (RTGDG) E-mode AlGaN/GaN HEMT is the capability to decrease the gate leakage and off-state leakage. Such low off-state leakage, high breakdown voltage, and high frequency enable this kind of GaN-based E-mode transistor very promising for high voltage drive circuit, low power, and high speed circuit applications.

In this paper, thermal treatment technique under NH₃ ambient for the recess surface of GaN-MOSFETs in order to remove plasma-induced damage is demonstrated. Atomically flat interface between SiO₂ and GaN at the recessed-gate and improved channel mobility of the MOSFETs are achieved utilizing the thermal treatment under appropriate temperature and NH₃ partial pressure.

Schematic drawing of the vertical blue LED chip grown by a mixed-source HVPE with multi-sliding boat system.

The colloidal quantum dots (QDs) embedded in polymer matrix agglomerate. When the distance between QDs becomes within several nanometers, an energy transfer without light emission occurs from small QD to large QD. To avoid this nonradiative energy transfer causing a significant redshift from the desired final color, a double layer polymer structure comprised of separated green and red emitting composite film is fabricated.

The molecular structure of fluorine resins with transmittance in DUV for encapsulating DUV-LEDs is clarified. The fluorine polymer incorporating (COCOC) rings caused the electrodes damage, resulting in device fault. The resin with the main chain of (CCCOC) terminated with CF3 ends is considered to guarantee no damage to the devices.

In this work, optical and electrical characteristics of direct current high voltage LEDs (DC-HV LEDs) and alternating current high voltage LEDs (AC-HV LEDs) are compared. The AC-HV LED has a relatively larger wall-plug efficiency than DC-HV LED over a specific current density range. It is found that light output power of AC-HV LEDs is dependent on both the number of working cells and the ratio of radiation area to total chip area.

Using selfconsistentelectrical-thermal-optical simulations, this paper analyzes general trends in variation of main light-emitting diode's (LED) characteristics under wide-range scaling of the device dimensions. Surface recombination at the open edges of LED active region, Auger recombination initiated by high electron and hole density in the active region, and temperature dependence of recombination coefficients are found to be the major factors controlling the LED efficiency. The revealed scaling trends are interpreted qualitatively in terms of a simple ABC-model, though quantitative predictions require elaborated numerical modeling.

In this paper the influence of the lattice strain in InGaN/GaN multiple-quantum-well solar cells on their performance by comparing the samples grown on sapphire and on AlN/sapphire template by metalorganic chemical vapor deposition is discussed. The experimental results indicate that a large compressive strain deteriorates the device performance owing to the generation of nonradiative recombination centers.

The influence of barrier thickness on the performance of InGaN/GaN multiple quantum well solar cells is investigated, showing that the thinner barrier favors the transport of photogenerated carriers but may be accompanied by larger leakage current. In addition, the detrimental effects of inadequate p-type doping and induced polarization field on the carrier collection are analyzed.

To improve the performance of deep-UV light emitting diodes (DUV-LEDs), the gradient electron blocking layers (GEBLs) are introduced. DUV-LED structures with different GEBLs are grown by high-temperature MOCVD. The electroluminescence intensity of the LED with 12-step EBL is approximately 2.3 times that of LED with single EBL at 280 nm. Also, all simulation data support the effect of a GEBL on DUV-LEDs.

In order to realize UVB light emitting diodes (LEDs) with high wall-plug efficiencies, the light extraction efficiency from the LED heterostructure must be maximized and operating voltages reduced. In this study, we investigate the effect of the GaN:Mg con-tact layer thickness on the light-output and current-voltage characteristics of UVB LEDs.

In this work UVC LEDs with emitting wavelengths as low as 230 nm and packaged powers averaging 0.1 mW are demonstrated. The shift in emission polarization across the wavelength region is displayed as a continuous function via photoluminescence. The lowest forward voltages to date at these wavelengths are achieved, and power output over time is investigated to demonstrate commercial feasibility.

This paper presents a new concept of deep-UV LED to overcome the doping issue of p-AlGaN. By adding a gate on the sidewall of the p-layer and the active area, the simulated wall plug efficiency of the structure is increased by a factor of 3 at a 3V lower working voltage.